An Inner Product Function Encryption Scheme for Secure Distance Calculation

With the continuous advancement of cloud computing, an increasing amount of data is being entrusted to Cloud Service Providers (CSPs) for hosting. Nonetheless, this trend has also raised concerns regarding data privacy. To ensure the protection of data privacy, it is advisable to encrypt the data prior to uploading. Functional Encryption (FE) is a novel multifunctional encryption paradigm that enables fine-grained access control over encrypted data stored on CSPs. By utilizing restricted functional keys, users can acquire knowledge of specific functions of encrypted messages while keeping other message information concealed. Inner product computation is a potent and straightforward functional within FE that can fulfill the requirements of numerous specific applications. This paper proposes an inner product function encryption scheme for secure distance calculation, enabling users to obtain the inner product functional value of encrypted data based on their location predicates. This distinctive FE scheme addresses the concern of location privacy protection, particularly in contact tracing applications for infectious disease cases.